Disruption of the NHR4 domain structure in AML1-ETO abrogates SON binding and promotes leukemogenesis.
AML1-ETO is generated from t(8;21)(q22;q22), which is a common form of chromosomal translocation associated with development of acute myeloid leukemia (AML). Although full-length AML1-ETO alone fails to promote leukemia because of its detrimental effects on cell proliferation, an alternatively spliced isoform, AML1-ETO9a, without its C-terminal NHR3/NHR4 domains, strongly induces leukemia. However, full-length AML1-ETO is a major form of fusion product in many t(8;21) AML patients, suggesting additional molecular mechanisms of t(8;21)-related leukemogenesis. Here, we report that disruption of the zinc-chelating structure in the NHR4 domain of AML1-ETO by replacing only one critical amino acid leads to rapid onset of leukemia, demonstrating that the NHR4 domain with the intact structure generates inhibitory effects on leukemogenesis. Furthermore, we identified SON, a DNA/RNA-binding domain containing protein, as a novel NHR4-interacting protein. Knock-down of SON by siRNA resulted in significant growth arrest, and disruption of the interaction between AML1-ETO and endogenous SON rescued cells from AML1-ETO-induced growth arrest, suggesting that SON is an indispensable factor for cell growth, and AML1-ETO binding to SON may trigger signals inhibiting leukemogenesis. In t(8;21) AML patient-derived primary leukemic cells and cell lines, abnormal cytoplasmic localization of SON was detected, which may keep cells proliferating in the presence of full-length AML1-ETO. These results uncovered the crucial role of the NHR4 domain in determination of cellular fate during AML1-ETO-associated leukemogenesis.
Ahn
Eun-Young
EY
Moores UCSD Cancer Center, University of California San Diego, La Jolla, CA 92093, USA.
Yan
Ming
M
Malakhova
Oxana A
OA
Lo
Miao-Chia
MC
Boyapati
Anita
A
Ommen
Hans Beier
HB
Hines
Robert
R
Hokland
Peter
P
Zhang
Dong-Er
DE
D000818:Animals; D001665:Binding Sites; D049109:Cell Proliferation; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics; D050676:Core Binding Factor Alpha 2 Subunit / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D020014:K562 Cells; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D015778:Minor Histocompatibility Antigens; D015514:Oncogene Proteins, Fusion / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D000075142:RUNX1 Translocation Partner 1 Protein; D014162:Transfection; D020298:U937 Cells
C107844:AML1-ETO fusion protein, human; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D015778:Minor Histocompatibility Antigens; D015514:Oncogene Proteins, Fusion; D000075142:RUNX1 Translocation Partner 1 Protein; C088203:SON protein, human